Shield for electrical conductors



Jan. 1, 1935. w BQYLE T AL 1,986,181

SHIELD FOR ELECTRICAL CONDUCTORS Filed March 2, 1935 2 Sheets-Sheet l|NVENTOR5 il/iih'am E30 19 and GIerziuood M. an Lear ATTO R N EYS 35- w,E. BOYLE ET AL 1,986,181

SHIELD FOR ELECTRICAL CONDUCTORS Filed March 2, 1933 2 Sheets-Sheet 2INVENTORS ll/171113712 E. Boyle and 67621111001 1M. lnzaw' ATTORNEYSPatented Jan. 1, 1935 UNITED STATES PATENT OFFICE SHIELD FOR ELECTRICALCONDUCTORS New Hampshire Application March 2, 1933, Serial No. 659,286

11 Claims.

This invention relates to a protective shield for encasing a body or apart thereof and more particularly the invention is concerned with ashield having a body formed of relatively stiff 5 material, the saidbody being yieldable to enable its arrangement upon the object withwhich it is associated and being adapted when thus arranged. to contractand firmly engage the object. The shield is characterized by featureswhich render it adavantageous as an electrical insulating sheath; as aguard against abrasion or wearing of a part of an object which, owing toits environment, is subjected to a rubbing contact with an adjacentobject; as a medium for preventing access of rain or moisture to theencased part; or as a means for reinforcing the object against bendingstrains or stresses.

For purposes of illustration the invention is described in connectionwith various forms of electrical conductors. When employed in thismanner the shield is adapted to be arranged around a part of theconductor which, owing to its close proximity to a limb of a tree orother contacting movable object is likely to be subjected to a rubbingor abrading action. The limb, or other object, therefore, rubs againstthe shield and injury to the conductor or impairment of the service isprevented. In this connection it is to be understood that this use ofthe invention is referred to by way of example only as the features bywhich the invention is characterized are such that it may be employed toadvantage in connection with various other forms of bodies, Whethermetallic or non-metallic and is not necessarily limited to electricalconductors.

One object of the invention is to provide a shield which may be securedeffectively and with facility in the desired position.

A further object is to provide a shield having high dielectricproperties of a permanent character.

A still further object is to provide a shield which will readilyaccommodate itself to bodies of various sizes.

45 A still further object is to provide a shield which is adapted toprevent penetration of water or moisture to that part of .the body whichit encases.

A still further object is to provide a shield 50 which isapplicable tovarious forms of electrical conductors, this object contemplating ashield which may be applied with equal facility to either insulated ornon-insulated conductors.

Embodiments of the invention are illustrated in the accompanyingdrawings, in which:

Figure 1 is a perspective view of a shield in which features of theinvention are incorporated, the shield being shown at an intermediatestage of its development.

Figure 2 is a perspective view of the shield in final form.

Figure 3 is a View partly in section and partly in elevation of theshield as applied to an insulated electrical conductor.

Figure 4 is a perspective view of the shield as applied to anon-insulated conductor, the shield in this embodiment includingsupplemental sealing means for preventing loosening of the variousconvolutions of the shield.

Figure 5 is a perspective View of a modified form of shield at anintermediate stage of its development.

Figure 6 is a transverse section taken along line 6-6 of Figure 5.

Figure '7 is a perspective View, in final form, of the shield shown inFigure 5.

Figure 8 is a perspective view, in final form, of another embodiment ofthe invention.

The shield, as illustrated in Figure 1, includes a body and a tailpiece16, both of which are of sheet-like form. The latter is preferably of agreater length than the former, while both are of substantially the samewidth. The body 15 consists of a base material which is preferably offabric-like character, for example, jute, paper, cloth, etc., the saidmaterial being impregnated in any suitable manner with a filler such as,for example, a phenol-formaldehyde condensation product or othersynthetic resin. The filler may include any desirable bituminous matter.

After the filler is applied to the base material and it has beenpermitted to dry to the extent desired the sheet thus provided issubjected to pressure and heat in accordance with conventional practice,whereby to cure the filler. When the filler is cured to the extentdesired the sheet, while still hot is formed in a tight roll and held inthis form in any suitable manner until it has cooled. When cool the bodywill retain its tubular shape (Figure 2) and while it can be unrolled itwill, when released, return to its tubular form with considerable force.

The tailpiece 16 may consist of any suitable insulating material offlexible or cloth-like character such as, for example, varnishedcambric, rubber or any other material which may be rolled and unrolledwithout impairing to an objectionable degree its di-electric properties.The tailpiece 16 is secured to the body 15in any suitable manner. Thismay be accomplished conveniently by arranging the body 15 and one end ofthe tailpiece upon one another during the application of pressure andheat to the body 15, whereby the latter and that portion of thetailpiece 16 which overlies the body are cemented together, it beingunderstood that the remainder of the tailpiece is not treated andretains its original condition. When the tailpiece is secured to thebody in this manner (Figure 1) the latter is rolled while hot into thespiral shape shown in Figure 2 and suitably held in this condition untilit has cooled in the manner described. It is to be understood that thebody 15 may be formed of some nonfibrous material such as, for example,celluloid or it may be, if desired, of laminated form. The purpose ofthe tailpiece 16 is to impart to the shield high di-electric propertieswhich are of a permanent character.

In the use of the shield, assinning its purpose is to protect aninsulated electrical conductor 17 (Figure 3) against injury from acontacting limb or other abrading object that part of the conductorwhich is to be protected is first covered with spirally wound doublefaced adhesive tape 18, the latter being wrapped around the insulatingcovering 19 of the conductor. The tailpiece 16 of the shield is thenwound tightly around the taped section thus provided, the tubular bodyapproaching the built-up section of insulation during this operation. Inaccordance with the invention the body 15 is unrolled and wound aroundthe insulating sheath which is provided by the convolutions of thetailpiece 16. In this operation the body 15 is unrolled against itsnormal tendency to retain its rolled shape and is arranged around theconductor. The contractile characteristics of the body 15 are relativelyhigh and hence when the body is arranged in the manner described andthen released it automatically contracts itself to firmly engage theconductor. The convolutions of the tailpiece tightly engage the tapedsection of the conductor and the shield is thus held against movementlengthwise of the conductor.

From the foregoing it will be apparent that when the shield is appliedin the manner described the various convolutions oi the tailpieceprovide an insulating sheath around that portion of the conductor whichis to be protected. The di-electrio properties of the tailpiece are highand hence possibility of injury to the insulating covering 19 of theconductor or the shield is negligible. The body 15 of the shield tightlyencases the insulating sheath provided by the tailpiece, therebyproviding a hard surfaced shell around the conductor which is highlyresistive to the abrading action of a tree limb or other movable objectwhich otherwise would rub against the conductor at this point. The body15, therefore, receives the abrading action of the limb or movable partand hence injury to the conductor or impairment in the service isprevented. It will further be apparent that owing to the resiliency ofthe body 15 and its tendency to retain a tubular form of predetermineddiameter that the shell may be applied with facility and when arrangedin the desired location will automatically contract to firmly engage theconductor. Loosening of the convolutions of the shield or movement ofthe latter along the conductor are, therefore, prevented without thenecessity of employing clamps or similar devices and the shield may beapplied without the aid of tools.

If desired, however, a strip of adhesive tape 20 (Figure 4) may beutilized to secure the convolutions of the shield when they haveadjusted themselves to engage the conductor in the manner described, thesaid strip being adapted to secure the outer end of the body to theadjacent convolution thereof. In this embodiment the shield is shown inconnection with a non-insulated conductor 21. In the use of the shieldin connection with a conductor of this type the conductor is taped as at22 (in a manner similar to the taping indicated at 18 in Figure 3)preferably throughout that portion of its extent which is to be encasedby the shield. After the application of the tape 22 the shield isapplied in the manner described in connection with Figure 3.

The invention contemplates the provision of a shield having thecharacteristics described wherein the material which imparts thedi-electric properties to the shield is (so-extensive with the body ofthe shield. The embodiment shown in Figure 5 includes a body 23 and alayer of insulating material 24. The former is similar to the body 15described in connection with Figure 1 while the layer 24 may be of anysuitable insulating material such as, for example, varnished cambric,rubber, asphalt paint, insulating varnish, or other material which willretain an imperforate condition. The body 23 is formed into a roll 25similar to the manner described in connection with Figures 1 and 2 andit may be applied to a conductor in substantially the same 1 manner. Itwill be apparent that the shield in this case consists of a plurality ofconvolutions of insulating material between which are disposed thevarious convolutions of the body 23. It is understood, of course, thatthe insulating layer 24 which is shown in Figure 5, as applied to thebody 23 prior to the formation of the latter into tubular form may beapplied to the body 23 after the latter has been formed into itspermanently rolled shape. The shield, therefore, similarly to the onedescribed in connection with Figure 1 has high di-electriccharacteristics as well as being capable of withstanding the abrasiveaction of objects which rub against it.

In the various embodiments illustrated the body 23 is formed of such alength that it is adapted to provide a plurality of convolutions whenapplied in the manner described. This has the advantage that the shieldmay be applied to objects of various sizes while at the same timeinsuring at least a single convolution of the body around the object. Inthe embodiment shown in Figure 8 the shield consists of a tubular body26 which is formed with a longitudinally extending slit 27, the saidbody being provided with a tailpiece 28 of insulating material which issimilar to and which functions in substantially the same manner as thetailpiece illustrated in Figure l. The body 26 is preferably treated inthe manner described in connection with Figures 2 and 7 whereby torender it highly resistive to abrasion. The tailpiece 28 is adapted toprovide an insulating sheath between the body 26 and the conductor uponwhich the body is arranged. It is flexible and the body 26 holds ittightly rolled upon the conductor and protects it against abrasion.

I claimas my invention:

1. A shield for an electrical conductor including a hollow body formedfrom av fabric material impregnated with a binder consisting of aphenolformaldehyde condensation product, said body being yieldable toenable its arrangement upon said conductor and being adapted when thusarranged to contract and firmly engage the conductor and a relativelyflexible sheet of insulating material carried by said body and adaptedto be wound around the conductor beneath said body during theapplication of the shield.

2. A shield for an electrical conductor including a spirally wound bodyformed from a sheet of material which is highly resistive to an abradingaction, the said body being so formed that while it may be unrolled toenable its arrangement upon said conductor it is adapted when thusarranged to contract and firmly engage the conductor and a sheet ofinsulating material carried by said body and adapted to be wound aroundthe conductor beneath said body during the application of the shield.

3. A shield for an electrical conductor including a relatively stiffhollow body formed from a sheet of material which is highly resistive toan abrading action and which is yieldable to enable its arrangement uponsaid conductor, said body being adapted when arranged to contract andfirmly engage the conductor and a relatively flexible sheet ofinsulating material which is secured to one end of said body and whichextends beyond said body in the form of a tailpiece, said sheet ofinsulating material being wound around the conductor beneath said bodyduring the application of the shield.

4. A shield for an electrical conductor includ-- ing a spirally woundbody formed from a sheet of material which is highly resistive to anabrading action, the said body being so formed that while it may beunrolled to enable its arrangement upon said conductor it is adaptedwhen arranged to contract and firmly engage said conductor and a sheetof varnished fabric carried by said body and adapted to be wound aroundthe conductor beneath said body during the application of the shield,said sheet being in the form of a tailpiece, whereby to provide aninsulating sheet around the conductor between the body and theconductor.

5. A shield for an electrical conductor including a relatively stifftubular body formed from a spirally wound sheet of material which ishighly resistive to an abrading action, said body being formed so thatit may be unrolled to enable its arrangement upon said conductor andbeing adapted when thus arranged to contract around said conductor and asheet of relatively flexible insulating material carried by said body inthe form of a tailpiece, the said last mentioned sheet being long enoughso that it may be wound around the said conductor to provide amulti-layer insulating sheath between said body and said conductor.

6. A shield for the purpose described including a relatively stifftubular body formed from a spirally wound sheet of material, said bodybeing so formed that it may be unrolled to enable its arrangement uponthe object with which it is associated and being adapted when thusarranged to contract and firmly engage the object and a sheet ofrelatively flexible material carried by said body in the form of atailpiece and being adapted to be wound around the object during theapplication of the shield.

'7. A shield for the purpose described including a relatively stifftubular body in the form or" a split tube, said body being so formedthat the adjacent ends may be separated to enable its arrangement uponthe object with which the shield is associated and being adapted whenthus arranged to contract and firmly engage said object and a sheet ofrelatively flexible material carried by said body and being adapted tobe wound around said object during the application of said shield.

8. A guard for an electrical conductor including a hollow body formedfrom a sheet of fabric material which is impregnated with a binderconsisting of a phenol-formaldehyde condensation product, said bodybeing relatively stiii but yieldable to enable its arrangement upon aconductor and being adapted when thus arranged to contract and firmlyengage the conductor and a relatively flexible sheet of insulatingmaterial secured to one end of the said body and being adapted to beWound around the conductor beneath said body during the application ofthe guard.

9. A guard for an electrical conductor including a hollow body formedfrom a sheet of fabric material which is impregnated with a binderconsisting of a phenol-formaldehyde condensation product, said bodybeing relatively stiff but yieldable to enable its arrangement upon aconductor and being adapted when thus arranged to contract and firmlyengage the conductor and a relatively fiexible sheet of varnishedcambric secured to one end of said body and being adapted to be woundaround the conductor beneath said body during the application of theguard.

10. A shield for the purpose described including a relatively stiff bodyof the shape of a split tube and formed from a fabric material which isimpregnated with a binder consisting of a phenolformaldehydecondensation product, said body being so formed that the adjacent endsmay be separated to enable its arrangement upon a conductor and beingadapted when thus arranged to contract around the conductor and a sheetof relatively flexible insulating material carried by said body andbeing adapted to be wound around said conductor beneath said shieldduring the application of the latter.

11. A shield for the purpose described including a relatively stiff bodyformed from a fabric material which is impregnated with a binderconsisting of a phenol-formaldehyde condensation product and which isrolled into a tube, said body being resilient enough to permit its beingopened and rolled upon a conductor and being adapted when released afterits application to contract upon the conductor and a layer of relativelyflexible insulating material applied to the inner side of the materialforming said body, said layer of material being capable of retaining itsdielectric properties while permitting the said body to be applied andto function in the manner described.

WILLIAM E. BOYLE. GLENWOOD M. VAN LEAR.

